Role of osteopontin in adhesion, migration, cell survival and bone remodeling.

Osteopontin (OPN) is a secreted adhesive glycophosphoprotein expressed by several cell types. It is normally produced in bone, teeth, kidney and epithelial lining tissues and is found in plasma and breast milk. It is involved in a number of physiologic and pathologic events including angiogenesis, apoptosis, inflammation, wound healing and tumor metastasis. In this review focus will be on OPN in bone and its role in adhesion, migration and cell survival. These aspects of OPN biology are important in tumorigenesis.